The present invention relates to a blade case suitable for storing an annular blade, particularly a washer type blade.
In the production process of a semiconductor device, a circuit such as an IC or LSI is each formed in a large number of regions arranged in a lattice form on the surface of a substantially disk-like semiconductor wafer and each region having the circuit formed therein is diced along predetermined cutting lines to produce semiconductor chips. Thus, the dicing machine for cutting the semiconductor wafer is provided with an annular blade, as a cutting means, mounted to a rotary spindle. Examples of this blade include a blade produced by binding diamond abrasive grains with a resin bond and having a thickness of around 100 xcexcm and a blade produced by binding diamond abrasive grains with nickel plating and having a thickness of around 20 xcexcm. Since all of them are easily broken due to small thickness, they are stored in a hard case and carefully handled until they are mounted to the rotary spindle.
As a blade case heretofore used comprises a circular holding means and a circular cover means to meet a shape of the annular blade, it is liable to roll. Therefore, there is a possibility that the blade case falls from a table and the blade stored therein may be broken. The holding means and the cover means are constructed separately and secured together by an adhesive tape after the blade is stored. Therefore, when the blade is to be mounted to the rotary spindle of the dicing machine, it takes time and labor to handle it, thereby reducing working efficiency and causing such a problem that the blade may be fallen and broken.
To eliminate the above problems, the present applicant proposes a blade case in which a holding means having a center hole support portion to which the center hole of a blade is be fitted and a cover means are formed as a unitary structure through a hinge and a side portion including at least the hinge is formed straight. This blade case is disclosed in JP-A 8-323545.
In use of the blade case disclosed in JP-A 8-323545, there is no problem when a so-called hub blade, which is produced by forming a blade at the periphery of a hub to be mounted to the rotary spindle of a dicing machine, is stored in the blade case, because the blade case can have a structure that the hub can be pressed by the inner wall of a cover means. However, when a so-called washer type blade having no hub for mounting the blade is stored in the blade case, the blade is difficult to fix securely and looseness is produced in the blade case, so that the blade may be broken during transportation. Further, to store blades which differ in the diameter of a center hole, a problem arises in that a plurality of blade cases having center hole support portion corresponding to the types of diameter of the center holes of the blades must be prepared.
It is an object of the present invention to provide a blade case capable of fixing reliably even a washer type blade therein in a state of it being stored in the case.
It is another object of the present invention to provide a blade case capable of storing blades which differ in the diameter of a center hole by exchanging a part of the component.
To attain the above objects, according to the present invention, there is provided a blade case for storing an annular blade having a center hole, which comprises a holding means having a bottom wall and a side wall formed upright from the outer periphery of the bottom wall and a cover means having a top wall and a side wall extending downward from the outer periphery of the top wall, the side wall being connected with the side wall constituting the holding means by a hinge so that the blade case can be opened or closed, wherein
the blade case further comprises:
a blade support means including a center hole support portion which is provided on the center top surface of the bottom wall of the holding means and to which the center hole of the blade is fitted and a blade supporting portion, formed on the outside of the center hole support portion, for placing the blade fitted to the center hole support portion;
a blade pressing-down means which is provided on the cover means and presses down the blade placed on the blade supporting portion, in a closed state that the holding means is closed with the cover means; and
a locking means which are formed on the side wall of the holding means and the side wall of the cover means and keep the closed state that the holding means is closed with the cover means.
The above blade pressing-down means comprises a blade pressing-down portion for pressing down the blade and a spring means for urging the blade pressing-down portion. Preferably, the center hole support portion and the blade supporting portion constituting the above blade support means are formed as a unitary structure and can be attached to and detached from the bottom wall of the above holding means. Further it is preferable that the peripheries of the above holding means and cover means have at least one straight portion and the holding means and the cover means are connected to each other by a hinge at the straight portion so that the blade case can be opened or closed and that a non-circular depression is formed in the bottom wall of the above holding means and a non-circular protrusion to be fitted to the non-circular depression is formed on the top wall of the above cover means. Preferably, the holding means, cover means and hinge are molded from polypropylene as a unitary structure.